What are the administrative requirements for obtaining a volunteer visa in Thailand for an expat organization?

For an organization to be able to hire volunteers they need to be registered with the department of Labour, and one other government agency, but I can't remember the other one. The legal requirements are basically the same as an ED visa. Every 90 days your visa has to be extended with the documents from the company verifying that you are in fact working. They also need to sponsor you for a work permit, as you can not do any kind of work without one, not even unpaid work. The people that are having problems are the ones that did not have the 90 day extensions in their passport. They only had the shady one year visa. If you were fluent in Thai you would be in high demand. As it is check with the private hospitals for possibilities.

I'd highly recommend education visa over volunteer. There's a huge crackdown going on right now with volunteer visas because they were used for years for people to stay when they shouldn't have been able to.

Getting one would require a lot more scrutiny than normal most likely, and could also limit your future options just because you ever had one on your record, legit or not.